Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
  • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
  • B07C5/02—Measures preceding sorting, e.g. arranging articles in a stream orientating

Definitions

• Our invention relates to an optical discrimination method and means for component orientation.
• Such an arrangement has two principal limitations: firstly, mechanical tooling can differentiate between components lying in various orientations only if the features which distinguish the orientations are mechanically detectable, and often they are not; secondly, it is seldom possible by means of mechanical tooling to re-orientate components which are not in a desired orientation.
• Each stage of mechanical tooling normally operates by rejecting and returning to the well of the bowl feeder any components lying in one of the undesired orientations. Where the geometry of the components is such that a high proportion is rejected because of undesired orientation the feed rate is seriously reduced, particularly in applications where there is a need for several tooling stages and hence several stages of rejection.
• optical discrimination is based upon the well-known fact that the pattern of light which is reflected by a component when it is illuminated differs according to the surface features of the portion of the component which is illuminated and hence that by monitoring the reflected light it is possible to determine in which orientation the component is lying. It has been found in practice that even when the surfaces of the component are not truly reflective the patterns of light scattered or reflected by those surfaces are frequently sufficiently distinctive to enable the orientation of the component to be determined. (The terms "optical” and "light” are used herein to include a wide range of electro ⁇ magnetic radiations extending from ultra-violet through visible radiation to infra-red and radio or micro-waves.)
• Optical systems overcome the principal limitations of mechanical discrimination, firstly because they are more versatile and are not dependent upon the surfaces being mechanically distinguishable; and secondly because the light received from the component can readily be turned into a signal which can be used to activate a reorientation device thereby providing a continuous stream of correctly orientated components without reducing the flow rate.
• GB-A-2,116,706 describes one particular method of using optical discrimination. It describes a system wherein the component is temporarily illuminated by a beam of light as a result of relative movement occurring between the component and the beam and wherein the orientation in which the component lies is determined by monitoring the response profile generated in a photoelectric detection system by the light scattered or reflected by surface features of the component.
• this method has limited applicability, firstly because it provides no ready means for coping with the situation which arises when a stable mode for transporting the component is not the optimum one for inspection purposes and, secondly, it provides no ready means for segregating the response received from features which distinguish the orientation from the response received from those features which are common to two or more orientations.
• the illumination of the component can be restricted to the local area within which distinguishing features may lie thereby obviating the need to segregate signals generated by distinguishing features from those generated by non-distinguishing features; secondly the component can be positioned relative to the light source and receiver so that the optimum response is received; thirdly, where necessary, the orientation of the component can be modified at the point of inspection to cope with the situation where distinguishing features are inconveniently positioned.
• this method is versatile enough to allow multi-positioning of a component or the use of multiple light sources to cope with a situation where the distinguishing feature or features do not all lie within one local area.
• our invention provides a method of orienting a stream of components, which components can assume any one of a small number of different stable orientations and have distinguishing features on one or more portions, comprising: arresting the motion of a said component and positioning it in relation to an incident beam of light so that said beam illuminates a local area within the component where a distinguishing feature will lie if the component is in a predetermined orientation, and monitoring the transmitted, scattered or reflected beam by photodetector means, said monitoring being synchronised with the positioning of the component to obtain an output from said photodetector means which is dependent substantially only on said local area; and using the output of said photodetector means to detect the orientation of the component and to effect any necessary reorientation to bring it into a desired orientation, or to segregate it from other components which have the desired orientation.
• the present invention overcomes the limitations inherent in the known system based upon interpreting the response profiles of the reflected or scattered light as successive areas of components are illuminated in sequence as they pass through a light beam.
• the method of our invention thus only monitors signals from the local area within which distinguishing features may lie.
• the movement of the component is arrested by suitable stop means prior to monitoring. It is preferred to bring the component into such a position relative to the light source and photodetector that the change in output signal from the photodetector according to whether or not a distinguishing feature is present within the local area is substantially optimised.
• the components may be fed onto a conveyor band through a metering device which works in synchronism with both the travel of the conveyor band and with the positioning of a shutter in front of a photo-electric receiver.
• the metering device will feed the components accurately into spaced positions along the conveyor band and the shutter will blank off the aperture of the photo-electric receiver until each component in turn is arrested and so positioned that the local area which may contain a distinguishing feature is illuminated by the light source.
• the shutter Simultaneously with the component arriving in this position the shutter will be withdrawn allowing reflected or scattered light from the local area to generate a signal in the photo-electric receiver.
• a signal is received from the local area the shutter will be replaced thereby preventing signals being received from features in other areas.
• Positioning mechanisms are used to bring components into the desired position relative to the light source and photodetector. These mechanisms will momentarily bring the components to rest and may move them in any direction relative to the conveyor band necessary to enable the optical system to provide a reliable signal.
• the aforesaid metering device may serve also as a positioning mechanism, i.e. the components may be monitored at the moment they are being metered. If desired, two or more local areas of said component may be monitored to detect its orientation about two or more axes.
• our invention neatly avoids the problem of having to segregate signals generated by distinguishing features from those generated by non-distinguishing features. It gives complete freedom for positioning the light source and receiver related to the component so that they can be placed where the optimum response will be received. It ensures that the response can always be maintained long enough to generate a reliable signal.
• the component allows the component to be positioned precisely relative to the light source and receiver and, where necessary, allows the orientation of the component to be modified during the period of illumination so that a confirmatory check on its orientation may be made. Futher ore it is versatile enough to allow multiple positioning of a component or the use of multiple light sources to cope with the situation where the distinguishing feature or features do not all lie within one local area.
• another aspect of our invention is a means for orienting a stream of components, which components can assume any one of a small number of different stable orientations and have distingushing features on one or more local areas, comprising: a light source and photodetector; means for arresting the motion of a said component and positioning it in relation to said light source and photodetector; means for monitoring the output from said photodetector in synchronism with the positioning of the component to obtain an output from said photodetector which is dependent substantially only on a determined local area of said component where a distinguishing feature will lie when the component is positioned; and means responsive to said output to effect a desired reorientation of the component or to segregate it from other components which have the desired orientation.
• Fig 1.- is a perspective view of an apparatus for carrying in-line components through three optical test stations.
• Fig 2 is a view of a typical component in its four possible orientations.
• Fig 3 shows the same component and defines the local areas where the component must be illuminated to determine its orientation.
• the requirement in this example is to present the components to the input stage of the next operation with the distinguishing feature (in this case a V-notch) on the leading edge and above the centre line of the component (as drawn) .
• the distinguishing feature in this case a V-notch
• This is achieved in two stages.
• the first stage the component is checked to determine where or not the notch lies on the trailing edge.
• a local area 10 (Fig 3) on the trailing edge which encompasses the position where the notch will lie if it is on the trailing edge either above or below the centre line is illuminated, so that if a notch is present a turn-around device can be activated to bring the notch to the leading edge.
• the second stage the component is checked to determine whether or not the notch, which is now always on the leading edge, is above or below the centre line.
• the apparatus comprises a conveyor belt 1 with a drive shaft 2 running to one side.
• the drive shaft actuates a metering device 3, and positioning mechanisms 4, 5, 6 and 7.
• the drive shaft is geared to the drive of the conveyor belt through bevel gearbox 28 and pulleys 29 so that the metering device and positioning mechanisms can be actuated in synchronism with the travel of the conveyor belt.
• the encoder 26 produces a digitised output dependent on the rotation of shaft 2.
• the output is fed to a controller (not shown) which is thereby enabled to energise positioning mechanisms 4, 5, 6 and 7 at the appropriate times.
• a single in-line stream of components 8 emerges from bowl feeder 17 and enters guide 18 in random orientation.
• the stream is carried by the conveyor belt to the metering device 3 which regulates the flow of the components by releasing them one at a time and accurately spacing them along the belt.
• Each spaced component is carried by the belt to positioning mechanism 4 which brings the component into the correct position for illumination by a light source 9 which projects a beam of light onto a local area 10 (Fig 3) on the trailing edge of the component.
• a convenient light source for use in this invention is an 0.5 mW helium-neon laser, but light sources extending over a wide range of electro-magnetic radiations have been used successfully.
• the light reflected from the illuminated area is received by a phototransistor 12 which is incorporated into a conventional detector circuit whose output is monitored only where the component has been arrested by positioning device 6.
• the output is applied to a first input of a voltage comparator, to a second input of which is applied a preset voltage derived from a constant voltage source.
• the voltage comparator is set to generate an output signal if, and only if, the voltage applied to the first input exceeds that applied to the second input.
• the output signal on line 30 is used to actuate the solenoid 11 of a turn-around device 27 if the pattern of reflected light indicates that the notch is on the trailing edge of the component.
• Positioning mechanism 4 is then mechanically withdrawn by cam 19 and bell crank 20 and the component is allowed to proceed along the conveyor belt to positioning mechanism 5 which retains the component in the correct position for illumination by light source 13, which projects a beam of light onto a local area 14 (Fig 3) on the leading edge of the component.
• the light reflected from the illuminated area is received by a phototransistor 15 which actuates a turn-over device 16 by a signal on line 31 to solenoid 25 if the pattern of reflected light indicates that the notch is within the illuminated area.
• the movement of the component is arrested by positioning mechanism 6.
• Positioning mechanism 6 is then mechanically withdrawn and the component allowed to proceed along the conveyor belt. All components arriving at this stage will have passed through both optical tests, and any necessary reorientations should have been effected so that all components will lie in the desired orientation. A final check is made at the third optical test station comprising positioning mechanism 7, light source 22 and photodetector 23. Any mis- oriented components are removed from the conveyor by a signal on line 32 to rejector means powered by solenoid 25. The third test station is only necessary if a very high integrity of the output components is needed, and in practice the rejector means will very seldom be activated.

Landscapes

• Sorting Of Articles (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Feeding Of Articles To Conveyors (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10585915

Family Applications (1)

Country Status (3)

Cited By (3)

Families Citing this family (1)

Citations (4)

• 1986
  • 1986-09-22 EP EP19860905382 patent/EP0238534A1/en not_active Withdrawn
  • 1986-09-22 WO PCT/GB1986/000564 patent/WO1987001976A1/en not_active Application Discontinuation
  • 1986-09-22 JP JP50490786A patent/JPS63500921A/ja active Pending

Patent Citations (4)

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